Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

• Effectiveness of E.coli DH5α biofilm to prevent MICD was studied.
• Conditions that lead to MICD were simulated by chemical acidification.
• Biofilm-covered mortar specimens were exposed to sulfuric acid solutions.
• The presence of biofilm helped reduce the chemically-induced mortar deterioration.
• Biofilm remained alive and continued to grow during the acidification process.

Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ~ 30 μm before acidification to ~ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack.